Hypotheses are free. You don't need "evidence" to form a hypothesis - you only need, at a minimum, a problem statement. The more hypothesis that are formed, the better the investigation will be. Some hypotheses will be supported by data (which can then be called "evidence" that supports the data) and some will be specifically refuted by data (which can then be referred to as "evidence" refuting the hypothesis.) In the end, a final hypothesis will be the one that is best supported by the data (evidence.)

This may be subtle but may go to the "theory-ladenness" of observations that philosophers (like Duhem, Kuhn and Feyerabend) discussed. Data gets meaning when evaluated against a hypothesis - otherwise it is just raw, meaningless data. You can collect all you want but until there is a hypothesis against which to evaluate the data; it may be noise or signal - it's sitting in a box waiting to be "assigned" value. The alarm going off at 1 am is indicative of an alarm going off at 1 am. If your hypothesis is that "a fire would activate the alarm system" then the data that the alarm activated supports the hypothesis. If the hypothesis is that "an alarm would activate near the time that the fire started (or at least when it achieved sufficient energy to meet the alarm activation parameters)" then the data that the alarm activated at around 1 am, evaluated against the hypothesis, provides support for the fire starting sometime just before 1 am.

I don't know how anyone else's brain works but I cannot help but form hypotheses as soon as I get an assignment (or used to.) What do you think when you receive a call for an alarm activation in a high-rise apartment complex at 5 PM? Can you form the hypothesis that this is probably food on the stove? You have no "evidence" yet (except the minimum - which is all you need). As you collect more data the hypothesis will either be supported or refuted. Is it "valid" in science to form hypotheses without evidence? Did Mendeleyev have "evidence" of the existence of elements where there were gaps in his table? He predicted (hypothesized) that an element (he called eka-silicon) would fit in a gap in his table (if his theory of periodicity was correct.) He hypothesized that in 1869 and in 1886, "germanium" was discovered with the properties Mendeleyev had hypothesized. Paul Dirac hypothesized the existence of "anti-electrons" in 1928 - "positrons were discovered in 1932. Einstein's general theory predicted gravitation lensing which wasn't shown to exist until 1919. The hypothesis, in and of itself, is neither "valid" nor "invalid" simply because it is postulated, with or without "evidence". One could argue that the argument that a hypothesis must be based on "evidence" could be considered circular if one accepts the premise that "evidence is data given meaning by evaluation against a hypothesis; that is, when it supports or refutes a hypothesis." How can you form a hypothesis if it requires data that supports or refutes itself?

Certainly, the number of potential hypotheses regarding a fire's origin or cause is very large but probably not infinite (although in practicality, the combinations of possible heat sources, fuels and circumstances that could bring them together is so large as to be, effectively, "infinite.") Fortunately, examination of the scene reduces the number of plausible ignition scenarios at a given, specific scene and they can be narrowed down from "infinite" to manageable. But the more hypotheses that the investigator formulates, the better their investigation will be - because they will have considered more possibilities. I can form the hypothesis "I bet the heat source was electricity" before I even arrive at a scene. If I arrive at the scene and there is no electricity, my hypothesis fails to be supported. The formation of the hypothesis is not "invalid" because fires can be caused by electrical events based on my knowledge, training and experience - Just not this one. And, the hypothesis, although it failed provides some defense against "confirmation bias" or "expectation bias" in that "I formed the hypothesis that the ignition source could be electricity. I looked for a potential refutational data and found it in the fact that there was no electrical service to the property. I then moved on to form other hypotheses."

The fact that 921 refers to "invalid" hypotheses is partly because I failed to submit a proposal to remove it before the deadline and is one area where I would play the 921 is a Guide" card and justify my deviation from that paragraph.

It is not a "negative corpus" methodology if there is data to support or refute the hypothesis. It seems that you are now trying to force that terminology ("negative corpus") into hypothesis development where it does not belong.


Steve